JPH0225508A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To prevent wear of furnace bottom refractory and to extend to service life of a blast furnace by blowing TiO2-containing raw material from a furnace bottom tuyere at the time of confirming the wear of the refractory at the furnace bottom part with a thermometer arranged in side wall at the furnace bottom part in the blast furnace and independently charging lump coke to center part of furnace top part in the blast furnace. CONSTITUTION:The thermometer 16 is arranged in the side wall at the furnace bottom part 12 in the blast furnace 10, to always observe the temp. of the refractory 17 at the furnace bottom part. When the temp. of the thermometer is abnormally raised, it is judged that the refractory 17 at the furnace bottom part is eroded, and the raw material containing much TiO2 of illmenite, etc., in a service tank 1 is charged into blowing tank 3 through an intermediate thank 2 and blown into the furnace from the tuyere 15 with carrier gas 5 under fluidizing condition by blowing of the gas 4, and at the same time, the coke having 30-50mm grain size is independently charged through a coke charging device 8 separately arranged to the raw material charging device. The eroded part of the refractory at the furnace bottom is fixed and repaired with the high m.p. TiO2-containing material and also by improving the gas penetration of coke layer at the furnace center part, molten iron and molten slag dripping down near the tuyere are reduced and the erosion of the refractory at the furnace bottom part is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a blast furnace operating method for preventing wear and tear on the bottom refractory of a blast furnace.

(Detailed Description of the Invention) In recent years, extending the life of blast furnaces has become an important issue from the perspective of reducing the cost of pig iron, and many improvements have been made to blast furnace operating methods, and the lifespan has now exceeded 10 years. ing.

One of the factors that affects the lifespan of a blast furnace is the wear and tear of the refractories inside the furnace. As the refractory wear progresses, cracks and melting damage occur in the furnace shell, and eventually hot metal flows out, ending the life of the blast furnace.

Therefore, various methods have been proposed to repair the worn parts of the refractories in the furnace.For example, for the shaft part,
The general method of repair is to reduce the size of the charge to the damaged area of the refractory and take a break to repair it.Repairing the bottom part of the lower part of the furnace and the bonshu area is performed by reducing the size of the charge to the level of the tuyere. An intermediate repair method has been implemented in Europe and the United States in which the air is stopped, the damaged parts are repaired in a short period of about one month, and the air is re-aired. However, damage to the refractories below the siding level at the bottom of the furnace cannot be completely repaired by the intermediate repair method described above.

On the other hand, in extending the life of a blast furnace, it is extremely important to know the remaining thickness of the furnace bottom side wall refractory. Methods for measuring the remaining thickness of refractories include, for example: ■Predicting based on the measured values of thermometers placed at regular intervals in the circumferential direction of the side wall of the furnace bottom and thermometers installed in multiple stages in the height direction. Method, ■
A method for estimating the erosion line of the hearth refractory using the hearth flow heat transfer model based on the temperature measurements of the hearth side wall and the hearth bottom (Tetsu to Hagane, Vol. 70.2224) ~
(p. 2231), (2) A method that is widely used in daily management of on-site operations and that involves continuously measuring the temperature at each location of the furnace body and predicting the wear and tear of refractories from the temperature change pattern.

By the measurement method described above, the wear and tear of the furnace bottom side wall refractories is W! If this is recognized, the conventional method is to strengthen the cooling of the worn part and increase the amount of Ti01 in the raw material charged to the blast furnace. Usually, the amount of Ti0g charged into the blast furnace is 3 to 4 Kg/p, t (p, t is 1 ton of pig iron,
However, if wear and tear on the bottom refractory is observed, increase the amount by 10 kg/p.

TiOx is reduced in the blast furnace and migrates into hot metal, and a portion thereof becomes a solid solution of TiN and TiC, so-called copper-colored titanium bare. Since this solid solution has a high melting point of 2000° C. or higher, it is known from the results of blast furnace dismantling surveys that it adheres to the worn parts of the furnace bottom side wall refractory and protects the worn parts. However, when the amount of TtCh is increased, Ti in the hot metal
As the TtOz content and TtOz content in the slag increases,
The viscosity of the molten slag increases (Akitoshi Shigemi, Ironmaking Handbook, Chijinshokan, pp. 244-247).As a result, the molten pig iron and slag cannot be discharged smoothly, forcing an increase in the number of blast furnace air reductions. , there are problems such as not achieving the planned pig iron output and increasing the coke ratio.

The Ti0tJi charged into the blast furnace is adjusted by changing the amount of iron sand containing Ti0i that is usually blended into the sintered ore raw material. In addition, if wear and tear on the side wall of the furnace bottom is confirmed and it is necessary to increase the amount of Ti0z charged, the amount of Ti0z charged to the blast furnace can be increased by adding illuminite powder with a high Ti1t content to the sintered ore raw material. We are trying to increase this number.

However, the average particle size of the sintered ore main raw material is 2 to 4 mm.

The average particle size of the auxiliary raw materials is 0.5 to 2 m-, whereas the average particle size of illuminite powder is fine, around 0.1 mm. inhibit sex. As a result, the bed layer thickness is forced to decrease, resulting in a decrease in the production rate of sintered ore, and there are problems such as an increase in the fuel consumption rate of coke breeze, coke oven gas, etc. and the electric power consumption rate.

Under these circumstances, an improved method for adding TiO2-containing powder to a blast furnace was disclosed in Japanese Patent Application Laid-Open No. 60-2286112. This method involves blowing Ti(h)-containing powder such as illuminite directly through the blast tuyere of the blast furnace. However, this method has the following drawbacks: (1) The tuyere TiO such as illuminite blown from
Most of the content is captured by the hot metal and slag dripping near the tuyeres, and is discharged outside the blast furnace as the iron is tapped and the slag is tapped, resulting in Ti compounds that stick to the worn parts of the refractories on the bottom side walls. yield is low.

(2) By injecting the Ti0z-containing body through the tuyere, the liquid permeability near the tuyere deteriorates, as well as the liquid permeability of the entire blast furnace hearth group, resulting in an increase in the coke ratio and a reduction in the amount of iron tapped. This results in a decline.

(Problems to be Solved by the Invention) An object of the present invention is to extend the life of a blast furnace by preventing wear and tear on refractories in the furnace in order to reduce the cost of producing pig iron. It is an object of the present invention to provide a blast furnace operating method that improves the retention rate of Ties compounds in the worn parts of the blast furnace and stops the progress of wear, while at the same time not causing deterioration of coke ratio or reduction of pig iron production.

(Means for Solving the Problems) As a result of various studies on preventing wear and tear of refractories in blast furnaces, the present inventors found that (a) appropriate particle size when introducing powdered stone containing TiO through the blast furnace tuyeres; If this amount of coke is charged into the center of the top of the blast furnace using a coke charging means provided separately from the bell-type charging device or the bellless-type charging device, the liquid permeability of the coke layer in the core is ensured, and the furnace The distribution of hot metal and slag in the radial direction of the bed changes,
The flow of hot metal and slag dripping near the tuyere is relatively reduced. (b) As a result, the capture ratio of TiO□ by the hot metal and slag dripping near the tuyere is reduced, so the refractory side wall of the furnace bottom is The yield of Ti compounds adhering to worn parts of objects is improved.

(C) Since the liquid permeability of the core is improved and the average liquid permeability of the hearth is not deteriorated, the coke ratio does not increase and the amount of iron tapped does not decrease.

These valuable findings led us to make this invention.

In other words, the gist of this invention is ``When the measured value of the thermometer installed on the bottom side wall of the blast furnace exceeds a predetermined temperature and wear and tear of the bottom side wall refractory is confirmed, TiO□-containing powder is removed from the tuyere. ``A method of operating a blast furnace in which coke with a particle size of 30 to 5 mm is charged into the center of the top of the blast furnace,'' and ``A method of operating a blast furnace in which coke with a particle size of 30 to 5 mm is charged into the center of the top of the blast furnace.'' TiO□-containing powder is injected from the tuyere in the direction in which the measured values exceed the specified temperature and the side wall refractories are damaged. At the same time, coke with a particle size of 30 to 50++ m is injected into the blast furnace. "A method of operating a blast furnace in which the material is charged into the center of the top."

(Function) Hereinafter, the case where the blast furnace operating method of the present invention is applied will be explained. FIG. 1 is a schematic cross-sectional view of a blast furnace having a bell-type charging device, in which 10 is the blast furnace main body, 11 is the top of the furnace, 12 is the bottom of the furnace, and 13 is a small bell.

14 is a large bell, 15 is a feather, 0.16 is a thermometer, and 17 is a furnace bottom side wall refractory. In such a blast furnace, when wear of the bottom side wall refractory 17 is confirmed by the thermometer 16 provided at the bottom of the furnace, the Ti island metal-containing powder is injected.

The blowing of the TiO□-containing powder is carried out as follows.
The TiCh-containing powder stored in the service tank 1 is introduced into the blowing tank 3 via the intermediate tank 2.

The Ti01i powder in the blowing tank 3 is fluidized by the gas 4 introduced from the bottom of the tank 3, transported by the carrier gas 5, passed through the distributor 6, and is sent to the blast furnace via the blowing nozzle 7 attached to the tuyere 15. blown inside. At the same time, instead of using the bell-type charging device (consisting of a small bell 13 and a large bell 14) provided at the furnace top 11, a separate coke charging device 8 (
(composed of a hopper 88 and a charging pipe 8b), coke with a particle size of 30 to 50 IIIm is charged into the center of the top of the blast furnace.

Further, since the wear of the furnace bottom side wall refractory does not necessarily occur uniformly, in that case, the Ti01i powder is injected only from the tuyeres in the direction where the temperature exceeds the predetermined temperature. Here, the upper limit of the coke particle size is set to 50 m5 or less because there is no ore near the coke charged in the center.
This is to prevent deterioration due to solubility loss, and the reason why the lower limit of the coke particle size is set to 301 or more is to ensure liquid permeability of the coke layer in the lower part of the furnace. The amount of coke charged into the core of the blast furnace is 1% of the total amount charged in the blast furnace.
It is preferably about 5% by weight. Further, as the TiO□-containing powder, powders such as illuminite, iron sand, anatase, and rutile can be used. The particle size may be determined as appropriate depending on the powder blowing method, blowing speed (feed rate), ratio of carrier gas to powder, and the like.

Although the blow tank 3 is shown as a blow tank type in FIG. 1, it is not limited thereto, and may be a rotary feeder 2, for example.

Further, the distributor 6 may be installed in plurality or in multiple stages as necessary.

The above explanation is for a bell-type blast furnace, but in the case of a bell-less type blast furnace, as shown in FIG. charged. The charging system for the TiO2-containing powder is exactly the same as in the case of the bell-type blast furnace, so the explanation will be omitted.

(Example) Hereinafter, a case will be described in which the blast furnace operating method of the present invention is implemented in a blast furnace having an internal volume of 5050 m'.

Table 1 shows the operating conditions and results. This table also includes the conventional method for comparison.

In the same table, the base indicates the operating state when there is no lithium wear on the bottom refractory. The Tiez-containing powder used in this example was Illuminite, and its component composition and particle size are as shown in Tables 2 and 3, respectively.

Now, in the case of the method of the present invention, as shown in Table 1, when the maximum temperature of the furnace bottom side wall refractory reaches 174"C, the blowing device shown in FIG. A total of 2,000 kg/h of illuminite powder was injected from the furnace, and at the same time, coke with a particle size of 30 to 50 m was charged from the coke charging device to the center of the furnace top at a rate of 8.9 kg.Such operation was continued for 6 days. As the process continued, the maximum temperature on the side wall of the bottom of the furnace reached 60°C.
°C or below, and the temperature has stabilized to the same level as the base operation. In this case, the adhesion yield of TiO□ compound to the bottom refractory is 1
As can be seen from Table 1, in the case of operation according to the present invention method, the amount of residual pig iron slightly increased compared to the base operation, but the blow pressure fluctuation index, number of slips, coke ratio, and pig iron tapping amount increased. In this case, there was no difference from the base operation.

In the conventional method, the maximum hearth temperature reached 172°C, so a total of 2,000 pieces of illuminite powder was collected from five tuyeres.
When the operation was continued in this state with the injection rate of Kg/h, it took 14 days for the temperature of the side wall refractory to drop to 60°C. In this case, the fixation yield of TtOx compound is 5%
It was low. In conventional operation, the amount of residual pig iron is 200 tons.
/d, the amount of residue deteriorated significantly to 70 t/d. Also,
The blow pressure fluctuation index, number of slips, coke ratio, and pig iron output were all worse compared to the base operation.

(Hereinafter, blank space) (Effect of the invention) As explained above, according to the blast furnace operating method of the present invention, the furnace bottom side wall refractory With this protection, the life of the blast furnace can be extended and the cost of producing pig iron can be reduced.

[Brief explanation of the drawing]

Figure 1 shows the Ti
A schematic cross-sectional view of a bell-type blast furnace equipped with a charging device for O2-containing powder and coke; FIG.
1 is a schematic cross-sectional view of the top of a bellless blast furnace equipped with a charging device for O*-containing powder and coke; FIG. 1 is a service tank, 2 is an intermediate tank, 3 is a blowing tank, 4 is a gas, 5 is a carrier gas, 6 is a distributor 27 is a blowing nozzle, 8 is a coke charging device, 10 is a blast furnace main body, 11 is a furnace top, 12 is the hearth bottom, 13 is the small bell, 14
15 is a large bell, 15 is a tuyere 116 is a thermometer, and 17 is a furnace bottom side wall refractory. -+); Zen 20

Claims (1)

[Claims] (1) When the measured value of the thermometer installed on the bottom side wall of the blast furnace exceeds a predetermined temperature and wear of the bottom side wall refractory is confirmed, TiO_2-containing powder is blown through the blast tuyeres, and A blast furnace operating method characterized by charging coke having a particle size of 30 to 50 mm into the center of the top of the blast furnace. (2) Air is blown in the direction where the measured values of multiple thermometers installed at regular intervals in the circumferential direction of the bottom side wall of the blast furnace exceed a predetermined temperature and wear and tear of the bottom side wall refractories is confirmed. TiO_ from the tuyere
1. A method for operating a blast furnace, which comprises blowing in powder containing 2-containing powder and charging coke having a particle size of 30 to 50 mm into the center of the top of the blast furnace.